The application of plastic shrink labels to containers is old in the art and, as set forth in U.S. Pat. No. 3,802,942, label material is cut in strips of predetermined length, wrapped around a mandrel and heat sealed to itself in an overlap seam. The resulting sleeve is telescoped over the container and then passed through a heated tunnel and the sleeve shrinks into conformity with the underlying container. These sleeves were usually positioned on the container such that the sleeve would shrink under the bearing surface, around the heel of the container and extend upward to adjacent the shoulder.
More recently, in U.S. Pat. No. 4,574,020, a process in which the container serves as the mandrel for the label and the wraparound of the label about the container by moving the leading edge of the label into contact with the container sidewall and tacking the label to the container, then rolling the container along the label until the trailing edge of the label overlaps the leading edge and is adhered thereto is disclosed. In this disclosed process the leading edge of the label is tacked to the container by applying a solvent to the label to form a solution with the plastic. This label is also contacted at its trailing edge by a solvent so the solution will form an adhesive for forming a completely formed and sealed sleeve of the label material. The sealed seam must withstand the forces generated when the container and label are passed through a heat shrink tunnel.
In the process set forth in the above-mentioned U.S. Pat. No. 4,574,020, the adhesive that is used is formed by dissolving a small finite area of the plastic label by applying a solvent thereto. The solvent, such as methyl methacrylate, is volatile and readily evaporates at room temperature. The solvent is applied to the label areas by contact with a gravure roll that carries the solvent applicating pattern in its surface. The solvent is applied to the gravure roll surface by contact with a fountain containing the solvent being held against the rotating surface of the gravure roll. Sufficient solvent is captured in the gravure pattern so that it will transfer by contact with the plastic label to cause it to form a solution and this solution acts as the adhesive for tacking the label to the container and forming a full height, overlapping seal that will withstand the tension produced by passing the label carrying container through a heat tunnel to cause the label to shrink, primarily circumferentially about the container.
The solvent is applied from a fountain and the excess solvent is doctored from the surface of the roll, but a thin film of the solvent will generally be left on the roll surface and this thin film will evaporate and cause the roll surface to become chilled. When the temperature of the roll surface drops below the dew point of the ambient air, there will be condensation of moisture on the roll surface. This water condensation will disturb the solvent transfer characteristics of the gravure roll and result in the label seal not being satisfactorily completed.